MILWAUKEE - At the University of Wisconsin-Milwaukee (UWM) Student Union, community members can get a free COVID-19 rapid test. Nasal swabs are processed on-site and results come back in about 15 minutes.
UWM’s community testing room uses the Abbot BinaxNOW test. This type of rapid test is an antigen test, and the campus health director says it’s about 95 percent accurate.
Depending on the outcome, the antigen test at UWM will be followed up with another test for confirmation. The follow-up test will be a PCR test, which will be more accurate. Swabs collected from community members are sent off-site to a lab. Results generally come back within a couple of days.
According to Dr. Aamir Saddiqi, UWM’s campus health director, rapid antigen tests can be useful as a screening tool, and for those who need frequent testing. Frequent testing improves the overall performance of the rapid test and can be valuable in limiting the spread of COVID-19.
Dr. Aamir Saddiqi
“An antigen test is good for surveillance,” said Saddiqi.
There are certain antigen test outcomes which are automatically followed up with a PCR test at UWM. That happens whenever a person has symptoms of the coronavirus, regardless of their rapid test result. A PCR test is also administered whenever a person tests positive.
“If it comes out positive, then you want to confirm it is truly positive,” said Saddiqi.
A lab that processes COVID-19 tests for hospitals like Froedtert and The Medical College of Wisconsin tells Contact 6 it is not doing antigen testing.
“We worry about false positives with the rapid testing, somewhere between three and five percent of all positive cases,” said Dr. Nathan Ledeboer of Wisconsin Diagnostic Laboratories.
Dr. Nathan Ledeboer
Wisconsin Diagnostic Laboratories does about 5,000 coronavirus tests a day, and has no plans to begin running antigen tests.
“If we start seeing demand that well exceeds our PCR testing capabilities then we would look at potentially replacing that,” said Ledeboer.
Before getting a COVID-19 test, Ledeboer recommends asking two questions of the provider. 1. How sensitive is the test? 2. How specific is it?
Sensitivity is a test’s ability to prevent false negatives. Specificity is its ability to not give false positives.
“You want to see a test in general that's going to be 90 to 98 percent sensitive and tests that are greater than 97% specific,” said Ledeboer.
Abbot claims its BinaxNOW test demonstrated sensitivity of 97.1% and specificity of 98.5% in a clinical study.
Upwards of 1,400 people a day have been making appointments at UWM for its rapid antigen testing. So far, about 13% of test results have come back positive.
Dr. Saddiqi says rapid tests can help prevent the spread of COVID-19, particularly when someone is alerted to a positive result.
“They can isolate themselves right away rather than waiting 3 to 4 days,” said Saddiqi.
The Contact 6 takeaway? Rapid antigen tests can be helpful as a screening tool or as part of a frequent testing regimen. However, you may want to follow-up with a PCR test for the final word.
For now, Ledeboer says several hospitals are sticking with PCR tests. Community testing sites run by the Wisconsin National Guard are doing the same.
There is a rapid PCR test available in some emergency rooms that gets results in under an hour.
A full list of University of Wisconsin System campuses offering rapid antigen tests at surge testing sites can be found at doineedacovid19test.com -- just click "Wisconsin."